Dictionary · Quality & Accreditation
Proficiency testing
Evaluation of participant performance against pre-established criteria by means of interlaboratory comparisons — an ISO/IEC 17025 requirement for demonstrating ongoing competence.
Related terms
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Check standard
A stable artifact or instrument measured regularly within a measurement assurance program; its control chart reveals drift, shifts, or loss of statistical control of the process.
NIST SOP 30 / GLP 1
Interlaboratory comparison
Organization, performance, and evaluation of measurements on the same or similar items by two or more laboratories under predetermined conditions.
ISO/IEC 17043:2023
Validation
Verification where the specified requirements are shown to be adequate for an intended use — demonstrating a procedure is fit for its purpose.
VIM (JCGM 200:2012) 2.45
Test uncertainty ratio (TUR)
The ratio of the tolerance of the unit under test to the expanded uncertainty of the measurement process used to test it. A 4:1 TUR is the traditional benchmark; lower ratios call for guard banding or risk analysis (ANSI/NCSL Z540.3).
ANSI/NCSL Z540.3
Test accuracy ratio (TAR)
The legacy ratio of unit-under-test tolerance to the accuracy specification of the standard used. Superseded in rigorous work by the test uncertainty ratio, which accounts for the whole measurement process.
Industry practice
Accreditation
Third-party attestation, by an authoritative body, of a conformity assessment body's competence to carry out specific tasks — for laboratories, against ISO/IEC 17025, by bodies operating under ISO/IEC 17011.
ISO/IEC 17011:2017